Here is an interesting issue that I thought I would share with the wider Odyssey community. A while ago I got an Check Engine Light (CEL) or Message Indicator Light (MIL). I went over to Autozone and got the code pulled. If you didn’t know you could do that, now you do. Autozone will pull those codes out of the on board computer for free.
They simply connect a device to the On-Board Diagnostic computer (OBD II) connector and it reads the codes in that computer. This can tell you a lot about what is wrong with your vehicle. So, next time you get a check engine light on, go to autozone and ask them to pull the codes for the check engine light. It’s that simple. Anyway, mine returned a P0401 error. At the time, I thought this was an EGR valve issue and replaced the EGR valve. That cost me around $100. It turns out that it probably was not the EGR valve at all as it would have thrown a different code for a stuck door on the valve. Anyway, let me back up a little.
EGR stands for Exhaust Gas Recirculation. It’s just a way to lower NOx (Nitrogen Oxide) emissions. What the EGR valve does is recirculate this harmful emission back into the air intake to be reburnt. That’s the high level explanation. Well, in Honda Odysseys, the EGR port from the intake manifold seems to be prone to getting clogged.
This exhibited itself in some very interesting symptoms which threw me at first because of a recall on transmissions on some Odysseys. That’s because a clogged EGR port on the manifold (the intake manifold simply takes the air from the air intake and allows it to enter the cylinders to aid in the burning of the fuel) can cause your engine to race or jump into gear at very odd times. So, it will exhibit symptoms that are very close to transmission symptoms. Just remember to pull all codes to rule out the transmission. If it all points to the EGR port/valve, then it probably is.
In the above picture, the intake manifold is below the engine cover. That’s the black plastic pictured there that looks like some kind of army vest with a 6 pack! Anyway, all you really have to do is take that intake manifold out, clear out the EGR port and reinstall. You will need to replace the upper intake manifold gasket that goes to the throttle body. There is also a throttle body gasket. You don’t have to replace both. To reset the engine code, simply disconnect the positive battery terminal for a few seconds.
I am attaching a document that outlines and diagrams disassembly. Some of it wasn’t right for me, but the gist is. Just use common sense to disconnect the electrical connections, bolts, etc. And make sure you keep track of what goes where for reassembly. The cost for this job: under $30 if you replace all gaskets up there. If you only do a few or one, it could cost you under $5. Btw, the bolt/screw removal on the throttle body is a pain because of the position. Have fun!
Also, the pdf doc I’m about to point you to is for an EGR kit where you drill a bigger hole for the EGR port in the manifold. I wouldn’t recommend it because it will simply clog again anyway. Save time, money, and frustration and just clear it out and reassemble. Here’s the Honda Odyssey EGR port cleaning tutorial. You can view that in your browser or right click on it and select “Save link as…”